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Ranjeev’s research on speciation in Tanzanian gastropods is published!

Ranjeev’s research on speciation in Tanzanian gastropods is published!

Congratulations to Ranjeev Epa (MS ’17)!  The research paper based on his MS thesis on systematics and morphology of Oligocene gastropods is now published in Papers in Paleontology.

Epa, Y.R., Stigall, A.L., Roberts, E.M., O’Brien, H., Stevens, N.J. 2018. Morphological diversification of ampullariid gastropods (Nsungwe Formation, late Oligocene, Rukwa Rift Basin) is coincident with onset of East African rifting. Papers in Palaeontology, 4:327-348.

Abstract:

A new freshwater gastropod fauna is described from the late Oligocene Nsungwe Formation of the Rukwa Rift Basin, Tanzania. Six new species of ampullariids are established including five species of Lanistes (L. microovum,L. nsungwensis, L. rukwaensis, L. songwellipticus and L. songweovum) and one species of Carnevalea (C. santiapillaii). These taxa occupy a morphospace region comparable to nearly half of extant Lanistes, a common and widespread genus in Africa and Madagascar. Palaeoecological evidence indicates that Nsungwe ampullariids inhabited fluvial, pond and paludal environments. Among these species are the oldest high‐spired and fluvially adapated Lanistes taxa. We suggest that Nsungwe Lanistes rapidly diversified in concert with habitat heterogeneity associated with the initiation of rifting along the western branch of the East African Rift System (EARS). Taxonomy, evolution and the biogeographical affinities of Nsungwe Formation freshwater gastropods contributes significantly to expanding the undersampled Palaeogene invertebrate fossil record of continental Africa.

 

Here is the university writeup about Ranjeev’s paper:

Paleontologists Find New Snail Species with Evolutionary Speed – Ohio University | College of Arts & Sciences

Snails may be physically rather slow, but the six new species identified by Ohio University researchers put on plenty of evolutionary speed when they had to. Ohio University paleontologists analyzing snail fossils from 24 to 26 million years ago have identified six new species-and published the first documentation of rapid …

 

Nilmani’s study of Ames Limestone Paleocommunities is published!

Nilmani’s study of Ames Limestone Paleocommunities is published!
So many beautiful brachiopods

Congratulations to Nilmani Perera (MS ’17)!  Her thesis project, which identified hierarchical biogeographic patterns in the paleo communities of the Pennsylvanian Ames Limestone has been published in Palaeogeography, Palaeoclimatology, Palaeoecology.

Perera, S.N. and Stigall, A.L. 2018. Identifying hierarchical spatial patterns within paleocommunities: An example from the Late Pennsylvanian Ames Limestone of the Appalachian basin. Palaeogeography, Palaeoclimatology, Palaeoecology, 506:1-11.

Abstract: Identifying ecological mechanisms that produce hierarchically arrayed spatial variation in community structure can be difficult in the fossil record due to conflation of spatial and temporal patterns. However, this difficulty can be mediated by minimizing the temporal duration of deposition within the unit examined. In this study, the fauna of the Upper Pennsylvanian Ames Limestone (Conemaugh Group) was analyzed to explore whether Ames paleocommunities exhibited hierarchical structure in a spatial dimension. This widespread carbonate unit was deposited during the maximum flooding interval of a glacio-eustatically influenced fifth order sea level cycle, and preserved taxa are contemporaneous within only a few thousand years. Paleocommunity structure and variability was assessed at multiple spatial scales using samples collected from seven outcrops of the Ames Limestone throughout southeastern Ohio which form a northeast to southwest trending transect parallel to the paleoshoreline. Abundance data were collected using quadrat sampling for brachiopods, bivalves, gastropods, bryozoa, corals, crinoids, echinoids, trilobites and foraminifera. Paleocommunity structure was analyzed via cluster, ordination, guild, and abundance analyses at multiple spatial scales (within a single locality, among localities and within the total study area) to provide insight on geographic partitioning of paleocommunity variation. Multiple levels of paleocommunity organization were recovered within the Ames fauna. All levels exhibited spatial partitioning, but the inferred proximate controls shifted from abiotic environmental controls at higher hierarchical levels to biotic controls at the lowest level. At the highest level, differentiation into a northern and southern regional paleocommunity was controlled primarily by substrate consistency and habitat heterogeneity related to variation in fluvial input within the basin. Local paleocommunity differentiation reflects biotic responses to topographic and environmental conditions that were geographically distributed within the region; whereas within outcrop variation was due largely to biotic feedback mechanisms.

Key points:

 

  • Paleoecology of a widespread, but temporally-restricted marine fauna was analyzed
  • Community analyses identified hierarchical constraints on spatial structure
  • Abiotic environmental controls were paramount at regional scales
  • Biotic interactions were primary at local scales
  • Hierarchical structure should be considered in paleocommunity analyses

 

Here is the university writeup about Nilmani’s paper:

Perera and Stigall Publish Study Detailing Ecological Structure of Local Fossil-Rich Limestone – Ohio University | College of Arts & Sciences

Generations of geology students at Ohio University have studied the Ames Limestone, the most fossiliferous rock layer in the Athens area, for class field trips and projects. This unit preserves skeletal remains of marine animals-corals, snails, brachiopods, trilobites, sharks- that inhabited a shallow sea that covered Athens about 300 million …

Two new publications on the Great Ordovician Biodiversification Event

Hot off the presses!  

The Stigall Lab has two new articles published in the Lethaia special issue “Contextualizing the Great Ordovician Biodiversificaiton Event”. This special issue derives from the IGCP 653 opening meeting in Durham in October 2016, and includes papers on many aspects of the GOBE and related topics.  You can access the entire issue online here.

Our lab has two contributions:

Stigall, A.L. 2018. How is biodiversity produced? Examining speciation processes during the Great Ordovician Biodiversification Event. Lethaia, 51 (2), 165-172. https://doi.org/10.1111/let.12232.

–In this paper, I make the case that it is critical to consider biological aspects of speciation, not only aggregate diversity counts, when seeking the causes of diversification events, such as the GOBE.

Trubovitz, S., & Stigall, A.L. 2018. Ecological revolution of Oklahoma’s rhynchonelliform brachiopod fauna during the Great Ordovician Biodiversification Event. Lethaia, 51(2), 277-285. https://doi.org/10.1111/let.12233.

–This is the second half of Sarah Trubovitz MS thesis, which examines community structure and body size in brachiopod communities across the GOBE in the Simpson Group of Oklahoma.

Bayesian estimation of Ordovician dispersal pathways

 

Today was an exciting day for the lab.  The paper on Ordovician dispersal pathways led by Adriane Lam which incorporates her primary MS thesis research came out. This paper is exciting for several reasons.  First, it’s always great when a student gets their research published! Second, this is the first use of bayesian biogeographic modeling with Paleozoic taxa.  Third, this project represents an evolution beyond a MS thesis project, through collaboration and improvements with additional authors at other institutions, namely Nick Matzke.  I am really so thrilled with how this paper came out.  It is a landmark is methods and has important implications for understanding Ordovician biogeography.  The only downside…Adriane titled it “Dispersal in the Ordovician” as  play on “Pirates of the Carribean” so I can’t get the Pirates theme song out of my head….

Lam, A.R., Stigall, A.L, Matzke, N.J. 2018. Dispersal in the Ordovician: Speciation patterns and paleobiogeographic analyses of brachiopods and trilobites. Palaeogeography, Palaeoclimatology, Palaeoecology, 489: 147-165. Online

Key Points:

  • Bayesian and ML methods were successfully implemented with Ordovician taxa.
  • Founder event speciation was important in the evolution of Paleozoic taxa.
  • Taxa with different larval strategies responded similarly to climate shifts.
  • Ocean currents were key influences on invertebrate dispersal patterns.
  • Results indicate most evolution within clades occurred during climate shifts.

 

Congratulations to our paleo group!

by Alycia Stigall

We had another great showing by our paleontology group at this year’s Department of Geological Sciences annual awards ceremony.

  • Outstanding graduating senior went to Emma Swaninger (Hembree lab)
  • Jenni Carnes (Hembree lab) was recognized at Outstanding TA
  • Ranjeev Epa (Stigall lab) received the Outstanding Graduate Student award
  • I was recognized for Outstanding Faculty Research and Outstanding Faculty Teaching.

It is really an honor to work these talented folks in our paleo group!

Ranjeev successfully defends this thesis!

by Alycia Stigall

Ranjeev passed the final defense of the MS thesis this morning after a lively presentation and discussion of Paleoecology of the Freshwater Ampullariidae from the Late Oligocene Nsungwe Formation of Tanzania. Ranjeev’s thesis describes a new fauna of freshwater gastropods documenting speciation during the initiation of the East African Rift Valley.  It’s a great study of an interesting and significant set of fossils.  Congratulations, Ranjeev!

Nilmani passes her final defense!

by Alycia Stigall

Nilmani is now a Master of Science!  She successfully defended her thesis titled: Hierarchical Spatial Patterns in Paleocommunities of the Late Pennsylvanian Ames Limestone.  Nilmani did a really nice job in her thesis analyzing and interpreting regional vs. local differentiation in contemporanous shallow marine communities across southeastern Ohio.  Congratulations, Nilmani!

 

Review paper on BIMEs: Biotic Immigration Events

Review paper on BIMEs: Biotic Immigration Events

I am extremely pleased to announce the latest paper from my research group.  This is a review of Biotic Immigration Events, which we term BIMEs, in the fossil record focusing on the ecological and evolutionary impacts that fossil large scale invasion events.  We consider examples from the Ordovician through Cenozoic in both marine and terrestrial systems.  The fossil data supports a two-phase diversity cycle in which the immigration event itself reduced speciation and causes faunal homogenization; whereas the subsequent basinal isolation is characterized by increased speculation and diversity accumulation at multiple levels.  We think this model has great potential as a null model to compare and contrast diversification patterns in the fossil record.  Perhaps my favorite part of this study, though, was working with Adriane, Davey, and Jen–former students that are now talented early career paleontologists in their own right.

Stigall, A.L., Bauer, J.E., Lam, A.L., Wright, D.A. 2017. Biotic immigration events, speciation, and the accumulation of biodiversity in deep time. Global and Planetary Change, 148: 242-257. Online

Geological Society of America Reflections

It is difficult to describe this year’s GSA meeting in Denver.  Overall, it was a great meeting, full of the usual pride in my students’ accomplishments, joy of reuniting with colleagues including many Stigall Lab alumni, nervousness about my own talks, and thrill of learning about the newest developments in the science of paleontology.  But I will always remember this meeting for the Paleontological Society banquet.

bear

The Stigall lab was busy presenting cutting-edge science on a wide variety of topics. Current MS students Ranjeev Epa and Nilmani Perera gave excellent poster presentations about Oligocene freshwater gastropods from Tanzania and Pennsylvanian marine community ecology of Ohio, respectively.  Recent alumnus Sarah Trubovitz gave a talk about her MS work on Ordovician brachiopod paleoecology, and I spoke about the importance of alternating dispersal and vicariance regimes in biodiversity accumulation.

ranjeev nilmani
We had a great Stig*Allstars (=name my alumni gave themselves) dinner to kick off the meeting.  Getting together with this talented group of former students turned colleagues is always a highlight.  They are doing such amazing work as PhD students and early career scientists. I’m so very proud of them and excited to see where their careers will go.

img_6525 img_6530

This year’s GSA, however, was really special as I was awarded the Charles Schuchert Award for Excellence and Promise in Paleontology from the Paleontological Society.  This was the 45th time the Schuchert Award has been presented.  It was only the 5th time that a woman received the award, and the first time a woman with children was the recipient.  After receiving the award from the Paleontological Society president, Steven Holland, I was honored to be able to give a short acceptance speech to the nearly 400 paleontologists gathered at our annual banquet.  I focused my remarks on the challenges to women and minorities in paleontology alongside the standard series of thank you’s.  This the first time that increasing participation has been addressed specifically in an award speech, and I felt both very compelled and nervous about making these comments.  I am very glad that I did!  Continuing to engage in conversations about women and minority challenges are very important for continued progress in our (or any) discipline.

Stigall Schuchert Speech schuchert

The full text of my speech is below, and it will eventually be published in the Journal of Paleontology.

RESPONSE BY ALYCIA L. STIGALL
For the Charles Schuchert Award, 25 September 2016

Thank you, Bruce, for your generous words. I deeply thank the Paleontological Society for recognizing me with this honor. I truly am very grateful and humbled to be selected as the 2016 Schuchert Award recipient. As a brachiopod worker from Cincinnati, the Charles Schuchert award holds special significance to me. I am also deeply honored to now be included among the prestigious set of 44 prior awardees. It is particularly gratifying as I am only the fifth woman to receive this award, and first woman who was a mother at the time of the award.

I am extremely thankful to be a paleontologist today. Paleontology is becoming an ever more inclusive and collaborative science. As I look out from this podium, I see a wonderful diversity of paleontologists –diversity of scientific approaches, diversity of focal taxa, diversity of gender, diversity of ethnicities and nationalities. Our diversity makes our discipline stronger.

However, barriers to full and equitable participation in science for women and minorities remain considerable. Implicit bias, higher expectations, under recognition, harassment, and isolation remain substantial concerns. As a society and as individuals, we are taking positive steps to increase dialog, foster support groups, promote awareness, and tackle our own inherent biases. Like all women who continue in science, I have overcome such challenges in my career, but tonight I stand here excited and optimistic that the future of our discipline will be one of ever increasing inclusion.

I would not be here tonight without the support of my family, colleagues, and friends, and I’d like to take the rest of my time to recognize some of them. First I must thank my parents. As teachers, they have been steadfast in their support of my love for learning, rocks, and fossils. When I was a child, they took me to national parks in 47 states, they accompanied me to rock and mineral shows, gave me a copy of a 1962 Golden Guide to Fossils, and allowed me to disappear into the nearby stream to hunt fossils for hours at a time. Those early experiences surrounded by loving support gave me the confidence to truly pursue my goals and dreams.

As an undergraduate at the Ohio State University, I had the amazing good fortune to learn morphology and systematics (with a Swedish accent) from Stig Bergström who taught me the importance of deeply understanding a clade and of adopting promising new approaches during one’s career. Loren Babcock instilled in me a sense of boundless enthusiasm for prehistoric creatures. And Bill Ausich taught me how to be an excellent scientific citizen, the importance of loving your clade, and above all pursing excellence in science. I am so thankful for the enduring support of Bill and Stig, which has been instrumental in my development as a scientist.

I graduated from OSU with a career goal to resolve early arthropod phylogeny–but quickly reoriented my research interests to studying the complex impacts of biogeography and ecological change on macroevolutionary patterns. In graduate school at the University of Kansas, I worked on phyllocarid crustacean phylogenetics of my master’s thesis, but rapid realized the limitations of working on uncommon fossils for my research agenda. So I shifted my focal taxon to rhynchonelliform brachiopods, and I haven’t look back. (Although I greatly enjoy working with conchostracans from time to time) Brachiopods are truly awesome.

Throughout graduate school, Bruce Lieberman was amazing mentor in every dimension of the word. He taught me how to construct a project, how to succeed in publications, and the importance of perseverance. Even beyond graduate school, Bruce’s promotion of my career has been immeasurable, and I thank him very deeply.

In my twelve years at Ohio University, I have been privileged to work with very supportive colleagues in our Geological Sciences department, an immensely talented set of paleontologists sprinkled across campus, and fantastic collaborators in the Patton College of Education. Working in a department with the master’s as our terminal degree offering, I’ve had the distinct pleasure of working very closely with each of my graduate students. My greatest scientific joy has been mentoring and encouraging my students—now numbering 13—as they develop from scientific novices to confident, accomplished scientists conducting research publishable in top journals. I am very proud of them, and certainly wouldn’t be standing here before you tonight without this exceptional group of students turned collaborators, many of whom are here to support me tonight.

Although I did not know many women paleontologist as a student, I have benefitted greatly from knowing and learning from many amazing women as a professional. In particular Margaret Fraiser, Sandy Carlson, Brenda Hunda, Lisa Park Boush, Dena Smith, and Peg Yaccobucci have been co-conspirators and role models in various ways. I thank the women who trailblazed in the cohorts ahead of mine, and I am greatly inspired by the women in the junior cohorts behind me.

I also thank my colleagues outside of this room. My approach to science has been considerably broadened and enriched by collaborations with modern biogeographers and ecologists as well my international colleagues with whom I’ve studied fossils on all seven continents.

Finally, and most importantly, I must thank my husband, Dan Hembree, who has been my partner in this journey since our first day of graduate school at Kansas. He has always believed in me, even when I did not. His friendship, laughter, encouragement, and discussions have made my science and my life so much richer, and I can’t imagine either without out him. Lastly, our children Max and Josie make everything awesome. It has been invigorating to re-explore the wonders of fossils through their young eyes.

Thank you again, to the members and Council of Paleontological Society for this recognition. I will strive to fulfill the promise inherent in this award and serve our community well in the years to come.

Eochonetes revision published

The final section of Jennifer Bauer’s MS thesis research, a substantial phylogenetic and morphometric analysis of the Late Ordovician brachiopod genera Eochonetes and Thaerodonta has (finally) been formally published in the Journal of Paleontology.

Bauer, J.E. & Stigall, A.L. 2016. A combined morphometric and phylogenetic revision of the Late Ordovician brachiopod genera Eochonetes and Thaerodonta. Journal of Paleontology, 90 (5): 888-909. Online

Cliff notes version: most of the species previously referred to either genus belong within Eochonetes, Thaerodonta is not a valid genus, and some of the previously referred species don’t belong to this clade at all.  Bonus fun: Jen named some new species including one for her amazing grandmothers and another for a character in her favorite book series.

I’m really very proud of Jen for her really excellent work on this project. I am also very pleased that we could clear up some of the confusing nomenclature around Cincinnati fossils.  The species variably known as Thaerodonta clarksvillensis and Eochonetes clarksvillensis is now definitively Eochonetes clarksvillensis.

clarky

*until someone else revises the genus at a later time